The Supreme Court agreed with Monsanto on Monday that an Indiana farmer’s un­or­tho­dox planting of the company’s genetically modified soybeans violated the agricultural giant’s patent.

The court unanimously rejected farmer Vernon Hugh Bowman’s argument that he was not violating Monsanto’s patent because the company’s pesticide-resistent “Roundup Ready” soybeans replicate themselves. Justice Elena Kagan said there is no such “seeds-are-special” exception to the law.

“We think that blame-the-bean defense tough to credit,” Kagan wrote. “Bowman was not a passive observer of his soybeans’ multiplication; or put another way, the seeds he purchased (miraculous though they might be in other respects) did not spontaneously create eight successive soybean crops.”

She added: “Bowman devised and executed a novel way to harvest crops from Roundup Ready seeds without paying the usual premium.”

While the case was about soybeans, the broader issue of patent protection is important to makers of vaccines, software and other products. Corporations were worried about what might happen if the decision had gone the other way.

But, as the justices had indicated at oral arguments in the case, they believed Bowman’s practices threaten the incentive for invention that is at the heart of patent law.

If someone could copy Monsanto’s product, “a patent would plummet in value after the first sale of the first item containing the invention,” Kagan wrote. “And that would result in less incentive for innovation than Congress wanted.”

Bowman acknowledged that his techniques were unusual.

The farmer purchased Roundup Ready soybeans for his first planting of the year on the 300 acres he farms in southern Indiana. At the time of the purchase, he agreed he would not save seeds from the crop for future planting.

But he did buy commodity soybeans, which are usually used for feed, from the local grain elevator for a second planting. As he hoped, those beans were mostly Roundup Ready — resistent to the weedkiller glyphosate — because that’s what most of his neighbors grow. He saved seed from those crops and bought more commodity beans for subsequent plantings.

Monsanto said Bowman’s planting violated the company’s patent. The U.S. Court of Appeals for the Federal Circuit agreed, rejecting Bowman’s argument that Monsanto’s right to control Bowman’s use of the seed ended when Bowman bought it, a legal concept called patent exhaustion. The court told Bowman to pay nearly $85,000 in damages.

Kagan cautioned that the unanimous ruling only concerned the case at hand, “rather than every one involving a self-replicating product.”

Kagan said the court recognizes “that such inventions are becoming ever more prevalent, complex, and diverse.” But she said the justices did not have to rule on how patent exhaustion would apply in other cases to decide that Bowman had violated the patent.